In the past, hermetic sealing of temperature sensitive semiconductor packages that utilized glass optical windows required high temperature fusing of the glass to the package housing. In such sealing process, a glass frit is applied to a package or glass, and the glass window is fused to the package via the glass frit.
The high temperature that is required to fuse the glass to the glass frit results in a degradation of the optical properties of the glass window. The high temperature requirement also can cause degradation or destruction of the semiconductor chip. Prior art processes utilized circular windows on the device lid.